[#872] Avoid calling broken Curl::Easy#http_put until Newrelic fix this
Added the banner about retirement into the README

Closes #882
Related: #881
[DOC] Update links to the new project pages

Closes #881
[ACTIVEMODEL] Added an example of facets in model search to integration test

Related: #879
Skipping model/concerns folder in the import Rake task

Closes #877
Added more errors to the `__host_unreachable_exceptions` list

Closes #871
Fixed possible double require of model classes

When loading environment berfor tire:import:all, it is possible that
models are already loaded when tire tries to load them. This can cause
redefinition of constants and all other kind of havoc.

This fix first tries to constantize the models to see if they are
already loaded before trying to require them.

See issue #744 for discussion.

Closes #869
Changed that `default` properties of Tire::Persistence are evaluated when being casted, not on class load

Closes #864
Add out_of_range? alias for Kaminari support

Kaminari's method is called "out_of_range?", but tire uses "out_of_bounds?". I added the alias to make integration with Kaminari easier.

Closes #855
Added support for bulk update

    # update mapping
    index = Tire::Index.new(Contact.tire.index_name)
    puts index.mapping(
      Contact.tire.document_type,
      properties: {
        updated_at: {
          type: 'date',
          format: 'date_time_no_millis'
        }
      }
    )

    # add data
    Contact.find_in_batches do |batch|
      documents = batch.map do |contact|
        {
          id: contact.id,
          type: Contact.tire.document_type,
          _routing: contact.account_id,
          doc: ContactSearchSerializer.new(contact, only: :updated_at).as_json
        }
      end
      puts index.bulk_update(documents)
    end

Closes #853